Antimycobacterial activity of cinnamate-based esters of the triterpenes betulinic, oleanolic and ursolic acids.

Betulinic acid, oleanolic acid and ursolic acid have been modified at the C-3 position to cinnamate-based esters and in vitro antimycobacterial activity against Mycobacterium tuberculosis H(37)Ra has been determined. The results indicated that modification of the parent structures of betulinic acid, oleanolic acid and ursolic acid to the p-coumarate and, in the case of the latter two triterpenes, the ferulate ester analogues resulted in high antimycobacterial activity. Structure-activity relationships within the lupane, oleanane and ursane analogues and between these triterpenes are discussed.

Antiplasmodial triterpenes from twigs of Gardenia saxatilis.

Ten triterpenes (1-10) were isolated and identified from the twigs of Gardenia saxatilis (Rubiaceae) and were subjected to antiplasmodial evaluation against the parasite Plasmodium falciparum. The first six compounds, lupenone (1), lupeol (2), betulinic acid (3), oleanolic acid (4), ursolic acid (5), and winchic acid (27-O-feruloyloxybetulinic acid) (6) were inactive in the assay. The other four compounds, messagenic acid A (7) and messagenic acid B (8), the 27-O-p-(Z)- and 27-O-p-(E)-coumarate esters of betulinic acid, and a mixture of uncarinic acid E (27-O-p-(E)-coumaroyloxyoleanolic acid) (9) and 27-O-p-(E)-coumaroyloxyursolic acid (10) exhibited antiplasmodial activity, with the IC50 values of 1.

Chemical modifications at the 22-hydroxyl group of ecdysteroids: alternative structural requirements for high moulting activity.

A number of 22-O-alkyl ether and acyl ester derivatives have been prepared and their moulting activity determined, using the Musca assay. It was found that a free 22-hydroxyl group is not an essential structural requirement for an ecdysteroid to exhibit high moulting activity. The activity of a 22-O-substituted ecdysteroid may even be higher than that of the parent compound, providing that the substituent constitutes a functional group that can enhance biological activity.